The present invention relates to unshaped refractory compositions based on fused cast oxides grains including a vitreous phase, these compositions being useful as jointing compositions and as moulding compositions.
The glass industry generally employs for the construction of its furnaces either fused cast or bonded refractory products of great purity, which products are highly resistant to corrosion by the glass. However, in order to render glasstight certain portions of the glass furnaces against infiltration of the molten glass which causes certain corrosion phenomena, it is necessary to employ unshaped refractory materials for jointing the blocks of refractory products. This problem exists more particularly for the hearths of glass furnaces where the glass infiltrates into the joints which exist between the slabs of either fused cast or bonded refractory products, corrodes the refractory materials employed to form the layer underlying the slabs (the bed), and then attacks the slabs themselves from below by a corrosion mechanism called "upward drilling".
The general idea of rendering a hearth of the glass furnace glasstight is described in French Pat. No. 818.571 which proposes for this purpose the use of a granular jointing matter consisting of free refractory granules free of binder, which sets, by sintering in situ, only when the furnace reaches its working temperature.
The solution proposed in this French patent has not, however, had a great success because of the difficulty in putting the jointing matter into place in the joints which may be of very small size.
The object of the present invention is to provide an unshaped refractory composition usable as jointing matter, in particular for the joints between the slabs in the hearth of a glass furnace, as well as for the manufacture by moulding of raw or fired refractory articles.